Firebase RecyclerView Adapter onBindViewHolder

Question

I'm trying to get data from Firebase to my RecyclerView by FirebaseRecyclerAdapter but it always set the list item to the initial value of the class

I am using data binding to set the class to a variable person.

Adapter class:

class RecyclerAdapterAllUser(options: FirebaseRecyclerOptions<PersonalInfo>) :
        FirebaseRecyclerAdapter<PersonalInfo, RecyclerAdapterAllUser.Holder>(options) {
        private lateinit var binding: ListItemAllUserRecyclerBinding
    
        class Holder(val binding: ListItemAllUserRecyclerBinding) :
            RecyclerView.ViewHolder(binding.root)
    
        override fun onBindViewHolder(holder: Holder, position: Int, model: PersonalInfo) {
    
            binding.person = model
        }
    }

class

class PersonalInfo() {
    var name: String =""
    var nickName: String = ""
    private var age = 0

    constructor(name: String, nickName: String, age: Int) : this() {
        this.name = name
        this.age = age
        this.nickName = nickName
    }
}

activity

class AllUsers : AppCompatActivity() {
    private lateinit var binding: ActivityAllUsresBinding
    private lateinit var adapter: RecyclerAdapterAllUser
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = DataBindingUtil.setContentView(this, R.layout.activity_all_usres)
        binding.listItemAllUsersActivity.hasFixedSize()
        binding.listItemAllUsersActivity.layoutManager = LinearLayoutManager(this)
        val options = FirebaseRecyclerOptions.Builder<PersonalInfo>()
            .setQuery(
                FirebaseDatabase.getInstance().getReference("users"),
                PersonalInfo::class.java
            )
            .build()
        adapter = RecyclerAdapterAllUser(options)
        binding.listItemAllUsersActivity.adapter = adapter
    }

    override fun onStart() {
        super.onStart()
        adapter.startListening()
    }

    override fun onStop() {
        super.onStop()
        adapter.stopListening()
    }
}

firebase database

chat-app-3ce78
users
    8tS5NqyvQUaLpo7oVbhCbhDnud82
        LogIn
        PersonalInfo
            age:18
            name: "mohamed"
            nickName: "komy"
    fTppKQYGMxbBPkMoM7A2aMwch332

Answer 1

The problem in your code lies in the fact that you're trying to use the following reference:

FirebaseDatabase.getInstance().getReference("users")

To display in you RecyclerView PersonalInfo objects. Please note, that this not possible since under users node, there are actually no such objects. An object of type PersonalInfo exists under PersonalInfo node, hence that behavior. Besides that, you also missing a child, which is 8tS5NqyvQUaLpo7oVbhCbhDnud82 , being the UID of the user that comes from the authentication process.

To solve this, you should use a query that looks like this:

val uid = FirebaseAuth.getInstance().currentUser!!.uid
val rootRef = FirebaseDatabase.getInstance().getReference()
val usersRef = rootRef.child("users")
val query = usersRef.orderByChild(uid + "/PersonalInfo/name")

This query object should be passed to the setQuery() method in order to get those objects displayed.